Interest in eating gluten-free is rising faster than baked goods containing the wheat protein that's proving problematic for many Americans.

The past five years have seen U.S. sales of gluten-free foods double to more than $1.5 billion, according to the market research company Packaged Facts. And the growth spurt is expected to continue at least through 2012 as more Americans are diagnosed with celiac disease or wheat allergies.

Yet about a quarter of U.S. adults are trying to reduce or completely forgo gluten for reasons that can't be measured in medical terms, according to industry and health care experts. Gluten-free devotees who lack diagnoses may be imitating celebrities, reacting to mass-media and marketing messages or experiencing a generalized sense of well-being from reduced consumption of wheat and processed foods.

Dowling isn't just responding to the latest dietary trend, acknowledged at the International Association of Culinary Professionals' April conference in Portland.

About three years ago, her husband, 61-year-old Joe Dowling, confirmed he was allergic to wheat. The couple's 26-year-old daughter, Maggie Nicholson, made a similar discovery within the past year. And Sandy Dowling, 61, caters to numerous clients at her Willows bed and breakfast who request gluten-free foods.

"It's becoming a huge trend," says Dowling. "There are more products out there ... which is amazing."

The gluten-free boom couldn't be more obvious to Dowling, who initially spent days in the kitchen developing recipes to accommodate her husband's condition and clients' special orders. Three years later, if Dowling doesn't have time to bake from scratch, she reaches for a high-quality, gluten-free mix. Pamela's is her preferred brand.

The chef is mindful, however, of the cost associated with premade baking mixes. One 19-ounce box, says Dowling, can be purchased for the price of an entire 5-pound sack of flour. Even blanched almonds — a naturally gluten-free medium for baking — purchased in the bulk section of grocery stores are far more economical than boxed ingredients, says Dowling.

"You shouldn't always have to pay so much for a gluten-free or wheat-free diet," says Dowling.

To save money, Dowling invests a little time to make her own mixes that can replace wheat flour in just about any recipe. The basic formula is 2 cups each sweet rice flour and brown rice flour and 1 cup each almond meal and tapioca starch. If she's baking muffins, Dowling adds 2 teaspoons of baking powder and 1/2 teaspoon of salt. If she's baking bread, she adds a package of yeast and 1 tablespoon of sugar.

"That can be what you keep in your canister on your kitchen counter," says Dowling of the resulting mixture.

The chef is quick to remind health-conscious cooks that they can't even consider reducing or omitting the salt or sugar. Salt is a necessary component of the chemical reaction with baking soda that causes quick breads to rise, she says. Sugar, she adds, feeds the yeast that puffs up bread dough.

In her years of testing recipes, Dowling has discovered that more salt and sugar are needed in gluten-free recipes than in standard, wheat-based ones — a point that apparently passed by some manufacturers of gluten-free mixes.

"That's the problem with these gluten-free mixes is they don't always rise," says Dowling.

The chef gives her gluten-free goodies extra lift with egg whites, whipped to stiff peaks and then folded into the batter. The addition of about three egg whites per recipe stands in for xantham gum, found in many gluten-free products.

In addition to avoiding xantham gum, Dowling says she steers clear of bean-based flours, which taste "just awful." The naturally gluten-free grains millet and sorghum are both sources of flour suitable for baking, she says.

Favoring quinoa and teff flours for their high nutritional values, Mary Shaw has adapted countless recipes for baked goods over decades teaching natural-foods cooking. As culinary educator for Ashland Food Co-op, Shaw has seen gluten-free dishes emerge recently as the No. 2 request for cooking-class topics.

"There's just an exponential increase," says Shaw. "It's kind of a force to be reckoned with."

Despite her own baking expertise, Shaw isn't personally restricted to a gluten-free diet. So she tapped a source for firsthand knowledge of gluten intolerance in Medford resident Joanie Kintscher.

"It looks like a huge wall to climb over," says Kintscher of diagnoses for celiac disease and gluten sensitivity.

Kintscher, 69, faced formidable barriers to simply understanding her condition when it first confronted her nearly three decades ago. At that time, gluten intolerance was lumped into the genre of food allergies, and little information was available outside books stocked in health-food stores, says Kintscher.

The college art instructor quickly came to terms with personally cooking everything she consumed to prevent digestive disturbances caused by wheat, rye and barley. Kintscher also focused on using the most healthful ingredients possible to create deceivingly delicious dishes.

Holiday favorites without the gluten are planned for Kintscher's next class, Dec. 2 at Ashland Food Co-op. Participants likely will learn preparation of yule logs, gingerbread and sugar-cookie cut-outs, as well as flour blends that can be substituted in these and other traditional recipes — or wrapped up for gluten-free gift-giving.